Accused murderer 'poisoned parents to death' with insulin, court hears

A woman allegedly told a former partner that "insulin is the perfect murder weapon" 16 years before injecting both her parents with a fatal dose, a court has heard.

Raelene Polymiadis, 65, of Craigmore, is standing trial in South Australia's Supreme Court accused of murdering her parents Brenda and Lynton Anderson — both 94 — by injecting them with "lethal doses of insulin" on separate occasions.

Ms Polymiadis, a type 1 diabetic, previously pleaded not guilty to two counts of murder.

Opening the trial, before a 14-person jury, prosecutor Michael Foundas said Mr and Mrs Anderson's lives were "deliberately cut short … by the actions of one of their children".

"It's the prosecution case that Ms Polymiadis deliberately administered fatal doses of insulin to her parents, killing them," he told the jury.

"She poisoned them to death, she murdered them."

Mr Foundas said that Ms Polymiadis had previously expressed knowledge about the effects of insulin for those who did not have diabetes.

"Prior to these events … about 16 years [prior], Ms Polymiadis had expressed to a previous partner … that 'insulin is the perfect murder weapon or way to kill somebody because it's natural in the body and can't be detected'," he told the jury.

"On the prosecution case, this comment reveals that Ms Polymiadis knew that insulin could be fatal and also reveals her belief that it is something that could not be detected."

Mr Foundas said that Ms Polymiadis's mother died from an insulin overdose on March 16, 2022, while at the Flinders Medical Centre.

"It's the prosecution case that on the 12th of March, during her attendance at the Noarlunga Hospital, Ms Polymiadis administered a large dose of insulin to her mum," he said.

Mr Foundas told the jury that Mrs Anderson was transferred to the Flinders Medical Centre where, it is alleged, Ms Polymiadis administered "a second dose of insulin to her mother" between March 13 and March 15, 2022.

"In doing so, the prosecution allege that she murdered her elderly mother," he said.

"Mrs Anderson was not a diabetic. Before the 12th of March, she was not suffering with any issues associated with her blood glucose levels. Nor with insulin production."

Mr Foundas told the jury that it was not until 14 months later, on May 1, 2023, that Mr Anderson, who also did not have diabetes, died after he was found unconscious on his kitchen floor with a "large amount of insulin within his body".

The jury was told that major crime investigators from SA Police did not get involved in the case until Mr Anderson's death.

"On the prosecution case, following the death of Mrs Anderson, the family were informed the matter had been referred to the coroner but there was no suggestion to them of a broader police investigation," Mr Foundas said.

"This, on the prosecution case, effectively meant from Mrs Polymiadis's perspective, she was operating under the belief she'd managed to murder her mother undetected."

'May never know exactly why'

Mr Foundas told the jury there was allegedly a "potential motive" behind Mr and Mrs Anderson's deaths.

"In this case, we may never know exactly why the reasons for the killing were," he said.

"One potential motive that arises on the prosecution case is perhaps a misplaced idea that killing her parents would spare them from going into a residential care facility — something both had expressed their clear preference against and the prospects of which were looming large.

"Whatever the reason for the killings, what will become clear on the prosecution case, is that both Mrs and Mr Anderson were administered lethal doses of insulin by Ms Polymiadis."

Mr Foundas told the jury that, being a diabetic, Ms Polymiadis had "easy access to insulin" and that it was the "same type of insulin used on each of [her parents]".

"On the prosecution case, when the circumstances of both deaths are considered together, when considered holistically, it raises the improbability of anyone other than Ms Polymiadis having administered the insulin," he said.

The trial is expected to run for three months and will hear evidence from various witnesses including family members and medical professionals.